Lessons · Python · ** raising to a power
Raising to a power
a ** b raises a to the power b: 2 ** 3 is 8. It is not multiplication.
Hone is a place to practise programming. This is one of its lessons, written out in full and free to read without an account.
What it is for
Compound interest, areas and volumes, how many combinations a four-digit PIN has, the size of a bit pattern: powers, not products.
How to think about it
Say it in words before you type it: 'two to the three' is 2 ** 3, 'two times three' is 2 * 3. A fractional exponent gives a root: 9 ** 0.5 is 3.0.
Worked example
print(2 ** 3)8.
print(2 * 3)6: a different operation.
print(10 ** 4)10000: how many four-digit PINs exist.
print(9 ** 0.5)3.0: a half power is a square root.
Your turn
Area of a square with side s.
area = s 2
Solve one with the tests running
The trap
-2 ** 2 is -4, because ** binds tighter than the minus sign. Write (-2) ** 2 when you mean the square of negative two.
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